×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

L7 versus B7 Bolting
2

L7 versus B7 Bolting

L7 versus B7 Bolting

(OP)
We have a low temperature piping application (-60 °C) we are installing.  Our pipe specification calls for either L7 or B8 bolting.

Most of this has been installed with B7 bolting instead.  The person that approved the use of B7 based his approval on the fact that the material specifications for B7 and L7 are virtually the same.

I reviewed this and they are very, very close with only slight deviation in allowable composition ranges.

So what's the real difference between L7 and B7?  Is it just a matter of pedigree?  Is there really some differences - i.e. heat treatment or other?  Bottom line:  are we facing a potential failure if we leave the B7 bolting in place?

I'd really like to know.

Thanks.

ProjEngKLS

RE: L7 versus B7 Bolting

L7 and B7 are both 4130 composition.  Both are quenched and both should be tempered.  The toughness check an L7 gets is a good indication that it was tempered.  We occasionaly see B7 that appear not to be tempered (Rc45) and would expect toughness to be poor.  But there is no check on a B7.

Note 4130 should not be used at a section over 2.5" as it has inadequate hardenability to assure bolting strength requirements.  

RE: L7 versus B7 Bolting

2
The main difference between SA-320 Grade L7 and SA-193 Grade B7 bolting is low temperature service. L7 bolting requires impact testing with 20 ft-lbs at -150 deg F. B7 bolting is for elevated temperature service. Impact testing is not required.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources